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Why does my more-efficient GSHP have lower tank temperatures?

The image below shows two model runs, both with a 0.5 kW GSHP. The 2014 one has a CoP of 2.14 and the 2040 one a CoP of 2.41. Other than that the systems are identical. The only other difference between the runs is that the external temperatures have been increased in the 2040 EPW.

image description

The power (labelled energy) seems right, but for some reason the water tank temperatures are consistently lower in the run with the higher CoP and external temperatures.

What could I check to try and figure out the root cause of this difference?

Why does my more-efficient GSHP have lower tank temperatures?

The image below shows two model runs, both with a 0.5 2.5 kW GSHP. The 2014 one has a CoP of 2.14 and the 2040 one a CoP of 2.41. Other than that the systems are identical. The only other difference between the runs is that the external temperatures have been increased in the 2040 EPW.

image description

The power (labelled energy) seems right, but for some reason the water tank temperatures are consistently lower in the run with the higher CoP and external temperatures.

What could I check to try and figure out the root cause of this difference?

Why does my more-efficient GSHP have lower tank temperatures?

The image below shows two model runs, both with a 2.5 kW GSHP. The 2014 one has a CoP of 2.14 and the 2040 one a CoP of 2.41. Other than that the systems are identical. The only other difference between the runs is that the external temperatures have been increased in the 2040 EPW.

image description

The power (labelled energy) seems right, but for some reason the water tank temperatures are consistently lower in the run with the higher CoP and external temperatures.

What could I check to try and figure out the root cause of this difference?